Trying to resolve sub-classing QThread - or not

[Kwakkie]

Check the updated documentation: http://qt-project.org/doc/qt-4.8/QThread.html . Basically:

class Worker : public QObject
 {
     Q_OBJECT
 
 public slots:
     void doWork() {
         ...
     }
 };
 
 void MyObject::putWorkerInAThread()
 {
     Worker *worker = new Worker;
     QThread *workerThread = new QThread(this);
 
     connect(workerThread, SIGNAL(started()), worker, SLOT(doWork()));
     connect(workerThread, SIGNAL(finished()), worker, SLOT(deleteLater()));
     worker->moveToThread(workerThread);
 
     // Starts an event loop, and emits workerThread->started()
     workerThread->start();
 }

class Worker : public QObject
 {
     Q_OBJECT

 public slots:
     void doWork() {
         ...
     }
 };

 void MyObject::putWorkerInAThread()
 {
     Worker *worker = new Worker;
     QThread *workerThread = new QThread(this);

     connect(workerThread, SIGNAL(started()), worker, SLOT(doWork()));
     connect(workerThread, SIGNAL(finished()), worker, SLOT(deleteLater()));
     worker->moveToThread(workerThread);

     // Starts an event loop, and emits workerThread->started()
     workerThread->start();
 }

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You can also connect the thread finished() signal to its own deleteLater slot.

I need to determine from a main thread in the UI that a worker thread has completed

You don't need to subclass for that. Either use the signal or check the isRunning from the main thread.

[astodolski]

You don't need to subclass for that. Either use the signal or check the isRunning from the main thread.

Which signal?

If checking isRunning, then it will always return true if calling from the man thread. I need to check the status of the worker object moved to the other thread.

My code's constuctor in FlashWizard.cpp:

FlashWizard::FlashWizard(QWidget *parent) : QWizard(parent), ui(new Ui::FlashWizard)
{
    ui->setupUi(this);
 
    ui->pbReading->reset();
    ui->pbWriting->reset();
 
    ui->lblReadingStatus->setText("");
    ui->lblReadingStatus->setText("");
    ui->lblProgStatus->setText("");
 
    connect(ui->introPage, SIGNAL(p1_updateLabelOne(const QString&)), this, SLOT(updateLabel(const QString&)));
    connect(this, SIGNAL(currentIdChanged(int)), this, SLOT(pageCleanUp(int)));
 
    worker = new Worker;
    workerThread = new QThread;
 
    worker->moveToThread(workerThread);
 
    connect(workerThread, SIGNAL(started()), worker, SLOT(start()));
    connect(worker, SIGNAL(finished()), workerThread, SLOT(quit()));
    connect(worker, SIGNAL(finished()), worker, SLOT(deleteLater()));
    connect(workerThread, SIGNAL(finished()), workerThread, SLOT(deleteLater()));
    connect(workerThread, SIGNAL(finished()), ui->programPage, SLOT(setDone()));
    connect(worker, SIGNAL(updateProgress(int)), this, SLOT(updateWritingProgressBar(int)));
    connect(worker, SIGNAL(finished()), ui->programPage, SLOT(setDone()));
    connect(workerThread, SIGNAL(finished()), worker, SLOT(stop()), Qt::QueuedConnection);
}

FlashWizard::FlashWizard(QWidget *parent) : QWizard(parent), ui(new Ui::FlashWizard)
{
    ui->setupUi(this);

    ui->pbReading->reset();
    ui->pbWriting->reset();

    ui->lblReadingStatus->setText("");
    ui->lblReadingStatus->setText("");
    ui->lblProgStatus->setText("");

    connect(ui->introPage, SIGNAL(p1_updateLabelOne(const QString&)), this, SLOT(updateLabel(const QString&)));
    connect(this, SIGNAL(currentIdChanged(int)), this, SLOT(pageCleanUp(int)));

    worker = new Worker;
    workerThread = new QThread;

    worker->moveToThread(workerThread);

    connect(workerThread, SIGNAL(started()), worker, SLOT(start()));
    connect(worker, SIGNAL(finished()), workerThread, SLOT(quit()));
    connect(worker, SIGNAL(finished()), worker, SLOT(deleteLater()));
    connect(workerThread, SIGNAL(finished()), workerThread, SLOT(deleteLater()));
    connect(workerThread, SIGNAL(finished()), ui->programPage, SLOT(setDone()));
    connect(worker, SIGNAL(updateProgress(int)), this, SLOT(updateWritingProgressBar(int)));
    connect(worker, SIGNAL(finished()), ui->programPage, SLOT(setDone()));
    connect(workerThread, SIGNAL(finished()), worker, SLOT(stop()), Qt::QueuedConnection);
}

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..and the worker.h

#ifndef WORKER_H
#define WORKER_H
 
#include <QObject>
#include <QTimer>
#include <QThread>
 
class Worker : public QObject
{
    Q_OBJECT
public:
    explicit Worker(QObject *parent = 0);
 
signals:
    void finished();
    void updateProgress(int);
 
public slots:
    void start();
    void stop();
    void doWork();
 
private:
    QTimer* m_workerTimer;
};
 
class MThread : public QThread
{
    Q_OBJECT
public:
    MThread(QObject *parent) :  QThread(parent) {}
 
    static void  sleep(unsigned long secs)
    {
        QThread::sleep(secs);
    }
 
    static void msleep(unsigned long msecs)
    {
        QThread::msleep(msecs);
    }
};
 
#endif // WORKER_H

#ifndef WORKER_H
#define WORKER_H

#include <QObject>
#include <QTimer>
#include <QThread>

class Worker : public QObject
{
    Q_OBJECT
public:
    explicit Worker(QObject *parent = 0);

signals:
    void finished();
    void updateProgress(int);

public slots:
    void start();
    void stop();
    void doWork();

private:
    QTimer* m_workerTimer;
};

class MThread : public QThread
{
    Q_OBJECT
public:
    MThread(QObject *parent) :  QThread(parent) {}

    static void  sleep(unsigned long secs)
    {
        QThread::sleep(secs);
    }

    static void msleep(unsigned long msecs)
    {
        QThread::msleep(msecs);
    }
};

#endif // WORKER_H

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Code

#include "worker.h"
#include <QThread>
#include <QDebug>
 
Worker::Worker(QObject *parent) : QObject(parent)
{
    m_workerTimer = new QTimer(this);
}
 
void Worker::start()
{
    connect(m_workerTimer, SIGNAL(timeout()), this, SLOT(doWork()));
    qDebug() << "Object constructor: " << thread();
    m_workerTimer->start(100);
}
 
void Worker::stop()
{
    m_workerTimer->stop();
    emit finished();
}
 
void Worker::doWork()
{
    for (int i = 0; i < 1000000; i++)
    {
        if (i % 10000 == 0)
        {
            emit updateProgress(i / 10000);
            qDebug() << (i / 10000);
            static_cast<MThread*>(QThread::currentThread())->msleep(10);
        }
    }
 
    emit updateProgress(100);
    emit finished();
}

#include "worker.h"
#include <QThread>
#include <QDebug>

Worker::Worker(QObject *parent) : QObject(parent)
{
    m_workerTimer = new QTimer(this);
}

void Worker::start()
{
    connect(m_workerTimer, SIGNAL(timeout()), this, SLOT(doWork()));
    qDebug() << "Object constructor: " << thread();
    m_workerTimer->start(100);
}

void Worker::stop()
{
    m_workerTimer->stop();
    emit finished();
}

void Worker::doWork()
{
    for (int i = 0; i < 1000000; i++)
    {
        if (i % 10000 == 0)
        {
            emit updateProgress(i / 10000);
            qDebug() << (i / 10000);
            static_cast<MThread*>(QThread::currentThread())->msleep(10);
        }
    }

    emit updateProgress(100);
    emit finished();
}

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[amleto]

Look, if you want to check workerThread->isFinished, then it isn't very clever to be deleting the workerThread when it is finished, is it?

If you remove this

connect(workerThread, SIGNAL(finished()), workerThread, SLOT(deleteLater()));

connect(workerThread, SIGNAL(finished()), workerThread, SLOT(deleteLater()));

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Then you can query workerThread->isFinished at any time you like.